foster



(No Model.)

T. FOSTER.

SAFETY VALVE. No.4 303,273.. Patented Aug. l2, 1884.

UNITED STATES aTENT EETeEc,

THOMAS FOSTER, DFMANCHESTER, COUNTY OF LANCASTER, ENGLAND, ASSIGNOB T() WTALTER FITZALLEN SIMPSOX, OF SAME PLACE.

SAFETY-VALVE,

SPLCFICATION forming part of Letters Patent No. 303,273, dated August 12, 1884.

Application filed April l, 1884. (No modelJ To @ZZ whom, t may concern.-

Be it known that l, Tnoiras FOSTER, a subject ol' the Queen of Great Britain, residing at Manchester, in the county of Lancaster,

England, engineer, have invented anew and useful Safety-Valve, of which the following is a specification.

My invention relates to improvements in safetyyalves; and the object o1" my improve` 1o ments is to increase the lift of thel valve on blowing off by guiding the issu-ing steam or other fluid, so as to causea vacuum or partial Vacuum on the upper surface of' the valve. I attain this object by the means illustrated in the accompanying drawing, which is a- Vertical section oi my improved safety-valve as adapted to the deadweight principle; but it may be loaded either by springs or weights in any oi' the usual I inake the valve a 2o preferably in the forni of an inverted cup,'al-

though it maybe in other convenient shape. The lip of the Valve rests upon a loose seating, 1;,which loose seating forms a lower Valve and rests upon an ordinary fixed seating, c, '25 secured to and carried by a stand-pipe, d. The loose seating b is made in the form of a short tube with a ilangc, b, at the upper end. This flange may vary considerably in size; but l prefer to make it about twice the di- 43o aineter of the valve when the working or blowing-off pressure is about one hundred pounds to the square inch and a proportionately less diameter for lower pressures.4 The outer portion of the flange b is so formed that its upper surface lies along and coincides, or nearly so, with the path of the steam or other lluid as it issues from under the lip of the valve a when blowing off, or, instead of coinciding with the outerportion of the ilange b', lo may be approximately parallel to the path of the issuing steam or other fluid, so that the pressure ol' the atmosphere shall be thereby swept from the said upper surface. I prefer to make the faceor lip of the Valve a hori- 45 zontal, in which case theouter portion ofthe flange t must also be approximately horizontal, because, when blowing oil", thesteam or other iluid leaves the valve in aline nearly straight and parallel to the faces vof the opening. The lip of the upper valve, a, andthe g lower face or lip of the loose seating l) need not be broader than is necessary to resist the eruslr ing-strain caused by the load placed upon the valve. I prefer to made the depth et' the loose seating l) about one inch andthree-quarters. lt may be made niuch deeper, but need not be deeper than is necessary to prevent the steam or other fluid as it issues from under its lower face from striking the under side of the tlange Z1',- nor must the issuing fluid pass so near this llange as to materially reduce the atmospheric pressure beneath it. An annular ilange or ring, c, may be attached to the guidef, for the purpose of further assisting to prevent the issuing iluid from sweeping the atmospheric pressure from the under side of the iiange b.

g is a tube which conveys steam or other fluid direct to the valve a, without reduction of pressure as the fluid passes the opening i? when blowing off. The diameter of the tube g may be from one-third to onehall" the diaineter ofthe Valve a., and the tube may be made longer than is shown in the drawing, il" desired, so as to extend into the steam-space of the boiler or other vessel to which the safety-valve is applied. The tube g is secured at the upper end to the loose seating b, and the lower end is or may be guided by ribs h. The valve a is guided by ribs i, and is loaded by means of annular weights placed upon a pendulous bonnet, k.

Having stated the nature of my invention, and described the manner of performing the same, I declare that whatl claim, and desire to secure by Letters Patent of the United States, irsl. The combination, with a safety-valve, u, of a loose seating, b, haring a flange, b', and connected to a tube, g, the lower end of said loose seating resting on xed seating, c, secured to a stand-pipe, d, the said stand-*pipe communicating with the boiler or other vessel, substantially as herein shown and described, for the purpose specified.

2.,In,c01nbination with a safety-valve and a lower seating, the loose seating b, providedV at its upper end with a flange, b,e;tendingbe 2' k 303,273 l f yond the body of said seating, and having its ments in safety-valves signed by me this 22d 1o upper face'in L plane coincident with or parday of March, 1884. ailel to the path of theissuing steam, substan- THOS FOSTER bially as set forth. 5 3. In a safety-valve, the combination, with Vitnesses:

the loose seating b, of the annular flange or C. A. BARLOW,

ring e, substannially as herein set forth,for lche S. WALKEY GILLETT, i

purpose specified. f Both of the Patent Oice, 17 St. Anns Square,

The foregoing specification of my improve- Mcmehester. 

